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[OatBran]

I know I know... this is 3 topic posts inside of a week... but I feel these are relatively important discussion points.

Anyhow... I've been playing with and experimenting with various dithering methods and am curious as to what all of you consider to be pertinent variables in determining what to use.

I couldn't help but notice that Mr. Brad Blackwood endorses Crane Songs CD dither!  Interesting.  I'd be interested in hearing it or atleast some material which used it.  With the crowds of simple and complex dithering schemes out there, I was curious which you use, for what reasons, and their implications.

Any takers?

[dcollins]

OatBran wrote on Fri, 21 May 2004 22:55

I couldn't help but notice that Mr. Brad Blackwood endorses Crane Songs CD dither!  Interesting.  I'd be interested in hearing it or atleast some material which used it.  With the crowds of simple and complex dithering schemes out there, I was curious which you use, for what reasons, and their implications.

I suspect that nine times out of ten B-rad doesn't use the Cranesong dither.

As you have probably deduced from reading the "internet," there is no single factor in mastering that will affect the sound more than dither.

Forget spending money on such luxurys as monitoring or acoustics, and start building your collection of different dithers and noise-shapers.  Like the pro's do.

Or, you just forget the whole thing, use a flat or low-order noisemaker and call it a day.

DC

[jfrigo]

My most frequent choice is flat TPDF dither, or perhaps some mild noise shaping if the situation calls for it. The difference between dither flavors is pretty low on the list of things to worry about. Just as long as you use dither, the type is less than an exciting decision. This may be a good time to mention the tech talk page at my website. If you want more in-depth thoughts, have a look. The first couple articles are some years old, but Nyquist & Shannon haven't changed their stripes since I wrote the articles in the 90's. Dither isn't exactly a new topic (though it is to some of course)...

[bblackwood]

dcollins wrote on Sat, 22 May 2004 01:51

I suspect that nine times out of ten B-rad doesn't use the Cranesong dither.

Or even less. On stuff suffering from a bad case of 'digititus' it can be a miracle worker, but for most projects, flat TPDF or POWr work fine...

Quote:

Forget spending money on such luxurys as monitoring or acoustics, and start building your collection of different dithers and noise-shapers.  Like the pro's do.

Excellent point, DC. If your room and monitors are the best you can possibly have and you eeked every bit of performance out of them, then you can start worrying about stuff that even experienced listeners have to hear in fairly controlled environments to discern.

Still never had a client comment on my selections of dithers. Or even ask about it, for that matter...

[jazzius]

It cracks me up every time i read someone over at Gearslutz talking about their favorite flavour of dither.....which they enjoy thru their Mackie monitors......the power of imagintion never ceases to amaze (me).

[TotalSonic]

dcollins wrote on Sat, 22 May 2004 07:51

Forget spending money on such luxurys as monitoring or acoustics, and start building your collection of different dithers and noise-shapers.  Like the pro's do.

Hee hee.  Hey Dave - I think you broke my online sarcasm detector's meters by slammin them to 11 with that one!

It seems what dither does for you is often misunderstood from what I've seen from a lot of general blather on the net.  This is all it will do for you: it smoothes out the sounds of things that fade out to the lowest dynamic levels - so that things like reverb tails instead of fizzling out as they get to the quiestest point blend into the noise floor instead. Good dither should have a few things: randomness, "pleasantness", and should be a tiny bit different on L & R channels (not in level - but in the noise being produced), and it's presence should be not apparent to the listener unless you really focus on it.

So whether the choice of it is critical is kind of dependent on the material and recording. i.e. A typical hip-hop master where the recording was made using 16bit samples & digital reverbs (which tend to fizzle out at the end of their tails anyway), and where the levels are usually pretty constantly slammed (where maybe the only time things fade to zero is at the end of the song) - what you use for dither - heck, whether you even bother to dither at all - really is not going to make any kind of appreciable difference (except for that final fade).  Contrast this with a recording done of say a string quartet done at 24 bit done in a live reverberant room where the material has a serious amount of dynamics and quiet passages - and then dither choice can be much more important as there are all kinds of things whose sound is fading into the distance that you'll want to preserve the natural characteristics of the ambience (which gives a sense of being there in the room) as much as possible.  

What the best thing to use is pretty subjective - and rather than trusting what the "experts" say it's best to judge for yourself.  
There are examples of various dither's noise cranked up so you can hear what the differences are at:  
http://www.24-96.net/dither/
Another way to check this out is to take a 24bit recording of something like, say a single strum on an acoustic guitar that fades to the distance in a really live room.  Process it to 16bit first truncating, and then using all your different dither options that you have. Listen back to the results and see what one you like the best.
Good headphones, good monitors, and a really quiet accurate room is pretty much a necessity for hearing the differences - because they are usually pretty subtle.

But ultimately what eq or comp you choose to set and what box is doing these things will have a much much greater impact on the vast majority of your masters than what dither you choose.

Best regards,
Steve Berson  

[OatBran]

I appreciate the relevant input from those of you who gave it!

I agree that dither is a kind of insignificant consideration. Especially now that converters have come so far from their inception.  In the 80's and early 90's, converters were still pretty bad and dither's need was higher.

However, this being a mastering forum where (I would hope) any details involved with the process can be discussed, I thought I would bring it up.  I found myself with a decision to make in session, however inconsequential, and I wanted to see what others were leaning to.  I was dealing with a 4 piece acoustic set with acoustic guitar, viola, vibes, and an acoustic bass.  In such a situation where dynamics are quite broad my dither choice had become more important.

Once again, thanks for the input.

[bblackwood]

OatBran, all things mastering are open for discussion. For the most part, posters on this board are helpful and stay on topic. I think the point of some of the posts above is that a new guy (not you, perhaps even a lurker), will read stuff about j*tter and dither and not fully understand how minor they are compared to whether or not you add .5dB at 10kHz. Too many people obsess about the little stuff while completely ignoring the major stuff like monitoring and room acoustics. And FYI, I'm quite sure I will always make that point when a discussion of dither and such comes up on my forum...

Again, I'd start with standard TPDF. I never really cared for POWr but needed something beside TPDF not too long ago as a certain project sounded quite a bit flatter at 16 than at 24. I tried POWr and it worked great on that project. Other times I've used POWr and could easily hear the diff on the dithered material, sounded brighter, if not harsher.

[jfrigo]

OatBran wrote on Sat, 22 May 2004 11:59

ecially now that converters have come so far from their inception.  In the 80's and early 90's, converters were still pretty bad and dither's need was higher.

You may have somewhat misunderstood the comments above. Dither is still needed just as much as it was in the 80's, regardless of the improvements in converters. That really has nothing to do with it. The part that was stated as less important is the choice of dither type. It was not stated that the USE of dither is unimportant. Proper dither practice is still quite important.

[OatBran]

Ah!  I see what you were getting at.  However, I do stand by my statement that dither is not as important as it was back in the 80's and early 90's...

Converters then were quite bad as we all know.  Not in the digital end as much as in the analog portions of the circuits.  The digital 'harshness' and the pitiful LSB (least significant bit) detail was absurd.  We were lucky to be getting 12bits of detail and 4 bits of crap.  Most of this was due to our inability at the time to create a steep yet clean anti-aliasing filter among other problems.  Phase issues wrecked the high end and the 96db theoretical dynamic range of 16bit never amounted to more then mid 80-85db at best after all was said and done.

Anywho, back then we had much more to clean up after as far as dither is concerned, IMHO.  This is not to undercut the necessity of dither now by any means.  If I thought dither to be unimportant, I wouldn't have brought this up.

Thanks all.

[Ronny]

What is this dither thing that you guys keep talking about? All that I can find on the internet is that it's a theolodic bombsight design, invented by Jimmy Stewart.

[dcollins]

OatBran wrote on Sat, 22 May 2004 14:01

Quote:

Ah!  I see what you were getting at.  However, I do stand by my statement that dither is not as important as it was back in the 80's and early 90's...

Not true.  When you have poor converter linearity, the dither doesn't work.   The LSB has to be meaningful for the system to do its thing.

Quote:

Converters then were quite bad as we all know.  Not in the digital end as much as in the analog portions of the circuits.  The digital 'harshness' and the pitiful LSB (least significant bit) detail was absurd.

Not really.  It was the converters, and to a lesser degree, the filters.  Take the Sony 1610 for example, Jensen transformers and 990's.  But fed to what?  JVC also had good analog designers.

Quote:

We were lucky to be getting 12bits of detail and 4 bits of crap.  Most of this was due to our inability at the time to create a steep yet clean anti-aliasing filter among other problems.

First, there _were_ A/D converters that came close to 16 bits in the old days, they were just expensive.  Analog Solutions comes to mind....  Second, the LPF's in the form of Murata and later Apolgee, were as linear as seven opamps in series can be...

Quote:

Phase issues wrecked the high end and the 96db theoretical dynamic range of 16bit never amounted to more then mid 80-85db at best after all was said and done.

This is arguable.  I have many, many, CD's that were mastered through brickwall analog filters where the high-end sounds terrific....  I was one of the first people to build custom all-pass filters to correct the HF phase shift of early PCM systems, but we gave up after finding the converter was the problem.

The ear is pretty much deaf to high frequency phase anyway.

Quote:

If I thought dither to be unimportant, I wouldn't have brought this up.

It's not _unimportant_ but just about everything else is more.....

DC

[lucey]

dcollins wrote on Sun, 23 May 2004 00:55

The ear is pretty much deaf to high frequency phase anyway.

define "high" ?

[dcollins]

lucey wrote on Tue, 25 May 2004 09:14

define "high" ?

Well, let's say deaf above 5kHz.  I think that's what Moore has.  Helmholtz said "phase deaf."   Then Harwood of the Beeb proved we weren't deaf, but not great either.  What is amazing is the brains ability to tell inter-channel differences of like 6 microseconds.  This does not mean you can hear 200kHz, btw.

Maybe with the right wire, though....

DC

[jfrigo]

dcollins wrote on Tue, 25 May 2004 22:11

What is amazing is the brains ability to tell inter-channel differences of like 6 microseconds.  This does not mean you can hear 200kHz, btw. Maybe with the right wire, though....

I try not to stick wires into my brain through my ears, but whatever works for you...